Colombian guerrillas kill 25 soldiers

Colombia's largest Marxist guerrilla group killed at least 25 soldiers over the weekend in the bloodiest fighting since the hardline president Alvaro Uribe took office three years ago.

Critics of his administration believe the attacks provide further evidence that Colombia's 40-year civil war is heating up, and that the guerrillas are not as weak as the president has claimed.

Fighting broke out in southwestern Putumayo state when up to 300 rebels of the Revolutionary Armed Forces of Colombia, Farc, ambushed an army convoy during an attack targeting nearby oil wells, said General Carlos Lemus, inspector general of the army.

Gen Lemus said at least 19 soldiers were killed, and announced a search and rescue operation for another 18 who went missing during the battles near Puerto Asis, some 330 miles south-west of Bogota. They were later found alive.

Putumayo is rich in oil and is one of Colombia's main cocaine-producing centres.

"We were engaged in very heavy fighting at dawn and called in air support," Gen Lemus told a news conference. "The attack was directed against petroleum installations."

Helicopter gunships attacked rebel positions in Putumayo while warplanes swooped down to drop bombs, he said. The rebels had also suffered casualties but Gen Lemus was unable to provide details.

On Saturday, government troops also launched an offensive to dislodge leftwing rebels blocking a road in north-east Colombia, leaving at least six soldiers dead, said General Edgar Ceballos, the local army commander.

Farc has been battling to topple the government in Colombia since 1964 in a conflict that kills more than 3,000 people every year.

The group, which has little popular support, funds itself through drug trafficking, kidnapping and extortion.

Thought to be 20,000 strong, Farc has this year launched some of its boldest attacks on the military since peace talks collapsed in February 2002, killing more than 130 soldiers and shattering notions that the rebels have been brought to their knees.

The US lists the group as a terrorist organisation and has given Colombia more than $3bn (£1.6bn) since 2000 to combat it and the drugs industry. The US calls Colombia the southern front in its "war on terror".

"This is a knock to us, a very, very hard one that means we must think about how we are going to change our policies," said President Uribe, who added that he was personally monitoring the situation.

The upswing in attacks comes as the military's largest ever offensive against the guerrillas appears to have had little effect. The "Patriot Plan" saw thousands of troops move to the south of Colombia in an effort to take the war to Farc's traditional stronghold.

The military had said one goal of the operation was to capture or kill members of the central command. Not one leading commander has been captured. In statements, Farc leaders have called the plan "a total failure".

Observers warn that attacks by the guerrillas are likely to increase in the run-up to next year's presidential elections.

President Uribe is seeking to change the constitution to allow him a second run at the presidency. If allowed to stand, it appears likely he will win again - his popularity ratings remain above 70%.

Mr Uribe and Farc share a mutual hatred. Mr Uribe's father was killed by Farc in a botched kidnapping, while Farc accuses the president of siding with the country's extreme rightwing death squads, a charge the president vehemently denies.